Heat exchange apparatus



July 6, 1937. A. M. HARKNESS 2,086,222

HEAT EXCHANGE APPARATUS Filed Hay 28, 1936 I 2 Sheets-Sheet 1 INVENTOR 4779 Mfizrfnmzs 7 M ATTO RN EY July 6, 1937. A. M. HARKNESS 2,086,222

HEAT EXCHANGE APPARATUS -Filed May '28, 1936 2 Sheets-Sheet 2 INVENTOR 412dre20/M/9grfina:

2 I BY Patented July 6, 1937 PATENT OFFICE v HEAT EXCHANGE APPARATUS Andrew M. Harkness, Nyack, N. Y., assignor to General Chemical Company, New York, N. Y., a corporation of New York I Application May 28, 1936, Serial No. 82,230-

9 Claims.

This invention relates to heat exchange apparatus, and particularly to cooling apparatus of the multiple tube type suitable for use in the.

For a fuller understanding of the nature and objects of the invention, reference is made to the following description taken in connection with 20 the accompanying drawings, in which Fig. 1 is a perspective of the improved heat exchange apparatus;

Fig. 2 is a perspective oi part of one tube unit showing the construction of individual tubes and 25 the grouping of the tubes with respect to each I other;

Fig. 3 is a horizontal cross-section taken on the line 33 of Fig. 2;

Fig. 4 is a horizontal cross-section taken on the 30 line 4-4 of Fig. 2; v I

Fig. 5 is a front elevation of a tube unit; and Figs. 6 and 7 are horizontal cross-sections, similar to Figs. 3 and 4, illustrating a modification; 35 Referring to Fig. 1, the heat exchange apparatus of the invention includes two tube units indicated generally by reference numerals I and ll. Unit HI comprisesa plurality of vertically disposed tubes l2, shown diagrammatically in 40 Fig. 1, opening into the under side of upper inlet header l3, having a closed rear end l4 and an open forward end l adapted to be connected to a fluid inlet pipe not shown. The bottoms of tubes l2 open into the top of an upwardly extend- 45 ing portion l8 ofa continuous U-shaped bottom' header 20 extending the length of the apparatus.

The upper ends of vertical tubes 2| of tube unit ll communicate with an upper outlet header 23 closed at the forward end 25, and open at the 50 rear .end 26 for connection to a fluid outlet pipe not shown. The lower ends of tubes 2| of unit I I open into the other upwardly extending portion 28 of the U-shaped bottom header 20. A supporting framework comprising cross-pieces 30, 3|,

65 and-32 and longitudinal sills 34, 35, 35, and 31 rest on a framework not shown, for example transverse beams beneath the ends of sills 34, 35, 36, and 31. The vertical .tubes and top headers of units l0 and H are supported in the relationship shown in Fig. l by posts 40 and the associ- 5 ated tie-rods 4|. I

Mounted on the top side of upper headers l3 and 23'are longitudinal overflow troughs 44 into which a cooling liquid such as water may be introduced from a pipe connection not shown; Reference numeral 45 represents a generally rectangular water sump positioned beneath the cooler-in such a way as to collect all of the water flowed down over theouter surfaces of the tubes from troughs 44. Passing through the horizontal portion of the U-shaped bottom header are several vertical pipes or passages 41 through which water collecting on the upper side of the bottom header 20' flows into sump 45; The apparatus is placed on the supporting framework in 20 such a way that the forward end is slightly lower than the rear so that condensate collecting in the continuous U-shaped bottom' header 2!] may be drawn 01f thru an outlet pipe 49.

Fig. 2 illustrates in perspective .part of unit ll (of Fig. 1) and shows upper header 23, four vertical tubes 50,5l, 52, and 53, and the upper part of the vertical portion 28 of the'bottom header 20. For convenience in the present discussion,

"dot-dash line 55 of Fig. 2 may be considered as 3o the longitudinal axis of the bottom header of tubes 50, 5!, 52, and 53.

Each individual tube, e. g. tube 50, is made by I indenting or compressing an initially cylindrical tube at intervals to form, a plurality of throats or constrictions 58, 59, 60, 6|, and 62 connecting a a series of what may be considered enlarged chambers 63, 64, 65, and 66. Fig. 3 shows a horizontal cross-section through adjacent tubes 50 and 5| taken .on the line 33 of Fig. 2,'and Fig. 4 shows a horizontal cross-section through tubes 50 andv 5| on the line 4'-4 of Fig. 2 through the next series of restrictions subjacent' to the restricv tions shown in Fig. 3. From Figs. 3 and 4 it will be seen that the tubes are indented so that restrictions form elongated throats having parallel side walls. As shown in Fig. 3, the horizontal axis 10 of throat 59 of tube lies in a horizontal plane disposed at a right angle to the vertical axis of tube 50. The axis ll of the next lower 50 throat 60 of pipe 50 also lies in a horizontal.

plane perpendicular to the'vertical axis of tube 50. but as shown in Fig. 4, axis H is disposed at a right angle to axis 10 of the next upper throat 59. Consequently all of the axes of throats of a 5 given tube are horizontal, and the axis of any one throat is disposed at a right angle with reference to the axis of an adjacent upper or lower throat.

In Figs. 3 and 4, the dot-dash lines 55 repre- 5 sent the longitudinal axis of the lower header portion 28, and dot-dash lines I5 and I8 represent the horizontal axes of throaw I8 and 18 of tube 5|. In accordance with the invention, the tubes comprising a given unit are grouped so 10 that as to adjacent tubes of a unit, (e. g. tubes 58 and 5|, Figs. 2, 3, and 4) adjacent tube throat axes lying in a common horizontal plane are disposed at an angle to each other and at an angle to the vertical plane of such adjacent tubes, or

in other words, at an angle to the vertical planeof the unit proper. Thus, as shown in Fig. 3, throat axes I8 and I5 lie in a common horizontal plane, and are disposed at an angle to each other and at an angle to the vertical plane including the longitudinal axis 55 of lower header portion 28, the vertical axes of the tubes and the longitudinal axis 82 of upper header 28.- Similarly, (Fig. 4) throat axes II and I6 lie in a common horizontal plane, and are disposed at an angle to each other and at an angle to the vertical plane including the vertical axis of the tubes and longitudinal header axes 55 and 82. In the embodiment of the invention. illustrated in the drawings, throat axes 10 and 15 (Fig. 3)

are disposed at an angle of 90 to each other and at an angle of 45 to the vertical plane of the tubes. The same relationship exists with respect to axes 'II and 18 of the adjacent lower throats 58 and 18 contact at point 85. Like-- wise, throat axes II and I8 of Fig. 4 intersect, 40 and the ends of throats 68 and I8 contact at point 86. In practice, the-tubes may be initially of relatively large diameter, for example 4 to 12 inches. The tube walls are usuallyfrelatively thin, and in many instances may be made of some particular metal to withstand corrosive eifects of materials being handled, as for example in the cooling of S02 burner gases in the manufacture of sulfuric acid, in which case the tubes may be made of lead. Thin walled lead tubes of such relatively large cross-section possess no material inherent rigidity and in a large unit would be likely to collapse in the absence of elaborate and expensive framework. The grouping of the tubes in accordance with the invention permits construction of the unit in such a way that tendency of the tubes to collapse is reduced to practically nothing and the amount of supporting framework may be'minimized. By reason of the grouping of the tubes,

00 all of the tubes of, a unit may be connected together to form a rigid structure by spot welding or, otherwise attaching adjacent tubes at each point of contact of the ends of the horizontal throat axes. In Fig. 3, the ends of throats58 c5 and I8 are spot welded at point 85, and in Fig.

4 the ends of throats 88 and 19 are spot welded spot welds 88 and 88 lie in a vertical plane rep-- resented by line 86, and spot welds 85 and 81 lie in a vertical plane represented by line 85. By this arrangement, adjacent tubes are attached in vertical planes spaced substantially to the front and rear of the vertical plane including the vertical axes of the tubes and the horizontal axes of the headers. The resulting structure has much more strength and rigidity than would be possible to obtain if the tubes were arranged in such fashion that the points of contact between adjacent tubes all were to lie in a single vertical plane/for example the vertical plane including the vertical axes of the tubes and the lon'gitudinalax'e's of the upper and lower headers. Furthermore, all contacts of the tubes are point contacts as-distinguished from line contacts. Additionally, the points of contact, by reason of their position at the ends of the throat axes.do not split or divide into streams a thin film of liquid flowed down over the outer, warped While it is preferred to construct the heat exchange apparatus so that individual tubes are grouped with respect to each other as described in connection with Figs. 2, 3, and 4, other arrangements of adjacent tube grouping may be employed and at the same time secure the advantages of the invention. For example, in the horizontal cross-sections of Figs.'6 and 7, corresponding in a general way with the horizontal cross-sections of Figs. 3 and 4, the horizontal throat axes I8I and I82 of throats I83 and I84 of tubes I85 and I88 lie in the same horizontal plane and ,are disposed at an angle of 120 to each other, and at an angle of 30 .withrespect to the dot-dash line I81 representing the horizontal projection of a vertical plane passing through the vertical, longitudinal axes of the' tubes. As shown in Fig. 7, the horizontal throat axes H8 and III of throats III and 8 are likewise disposed at an angle of 120 to each other and at an angle of 30 to dot-dash line I81. Whereas in tube 58, (Figs. 3 and 4) adjacent throats of a given .tube are disposed at an angle of 90 to each other, in the modification throats I88 and II! of tube I85 are disposed to each other in the or 120 angular relation shown in Figs. 6 and 7. In the modified construction of Figs. 6 and 7, it will be seen that the horizontal throat axes lying in a given horizontal plane intersect and the ends of the throats approximately touch (as in Figs. 3 and 4) thus making possible spot welding as at points H5 and H5, or in other words, in vertical planes spaced substantially to the front and to the rear of the vertical plane passing through the vertical longitudinal axes of the tubes.

Individual tubes used to make up the cooler unit such as shown in Figs. 2, 3, and 4 may be made from cylindrical tubes of any suitable material and of any desired length and diameter.

-- In the preferred embodiment of the invention of Figs. 2, 3, and 4, individual tubes may be made from cylindrical lead tubes, having an initial diameter of about 6 inches, by flattening the tubes at about 7% inch intervals at an angle of about 90 between successive throats or crimps. The tubes may be crimped so as to provide about half inch clearance between the inner elongated parallel walls of the throats. Fluid flowing.

through the tubes has a high velocity while passing through the throats and then a much lower velocity while passing through the expanded chambers intermediate the throats. Gaseous, vaporous, or liquid medium passing through the tubes is subjected to extremely vigorous turbulence and mixing, thus favoring efficient transfer of heat to or from the walls of the tubes depending upon whether the apparatus is used to cool or to heat the material flowing through the tubes. In the case of tubes of the type and size mentioned, the ratio of the cross-sectional area of the tubes to the cross-sectional area of the throats is about 6.25:1. By making the tubes so that the successive throats of a given tube are at an angle of about 90 as in the preferred construction, it is practically impossible for the fiuid passing throughthe tubes to core, since the ratio of the cross-sectional area of the tube to the direct unobstructed passageway through the tubes is about 113:1. Accordingly, fluid flowing through the tubes is constantly subjected to changingforces, causing efficient mixing and substantial elimination of film formation on the inner walls of'the tubes. While 6 inch tubes crimped at intervals of about 7 /2 inches have been mentioned, other ratios of tube diameter to distance between successive throats may be employed although the ratio of diameter to distance between successive throats should be about five to four or more.

The apparatus of the invention may be used for cooling or heating'liquids and gases; for condensing of vapors from gases; for removal of finely divided liquids or solids from a gas stream; for mixing gases, mixing liquids, gases and liquids, and liquids and solids: and for absorption'or stripping gases or vapors by liquids. The apparatus may be employed for example for the cooling of acids as described in Carter U. S. Patent No. 1,943,855 of January 16, 1934. In this case, one or both of the units of the apparatus of the invention may be used, and if one unit only is employed, it will be understood that a lower header similar to an upper header will be used instead of U-shaped bottom header 20 shown in the drawings. a

The apparatus of the invention is also particularly adaptable for use in cooling of S02 burner gases in the manufacture of sulfuric acid. For example, the apparatusshown in Fig. 1 of the drawings may be employed in a wet purification system such as shown in Herreshotf U. S. Patent apparatus of the invention between the third cooling tower F and the coke-box O of the Herreshoff patent. When so employed, the S02 burner gases are introduced into the upper header l3 through the open end [5 at temperatures of about 300. F. Water is fed into'overfiow boxes 44 on topsides of headers l3 and 23 so that the cooling water'flows downwardly over the outer surfaces of the tubes in the form of continuous thin films. Flow of gas through the apparatus of Fig. 1 and rate of flow of cooling liquid over the outer surfaces of the tubes are controlled so that the gas leaving-the rear end of header 23 is at temperatures of about 100 F. During passage of the SO: gases through the cooler moisture'and sulfuric acid in the form of mist are condensed out, collect in the bottom of U-shaped header 20, and such condensate is withdrawn through outlet pipe 49. In this connection, it is noted that heat transfer is more flicient in the downflow unit It than in the upflow unit I I. In unit "I, the gas, vapors, and condensate formed are all flowing downwardly and downflow of the gas readily carries condensate along with the gas" stream and formation of a liquid film on the inner tube walls is minimized. In unit ll, upflow of gas tends to which is disposed at an angle to the longitudinal axis of the tube, the axis of one throat being disposed at an angle to the axis of the next adjacent throat in said tube, adjacent tubes being arranged parallel and so that adjacent tube throat axes lying in the same plane are disposed at an angle to each other and at an angle to the plane of adjacent tubes, and means connecting adjacent tubes approximately at points where the ends of adjacent tube throat axes lying in the same plane mostclosely approach each other.

2. Heat exchange apparatus comprising-a plurality of tubes, each tube including a plurality of restricted throats and a plurality of chambers connected by a restricted elongated throat hav-- ing an elongated cross-section the longest axis of which is'disposed at an angle to the longitudinal axis of the tube, the axis of one throat being disposed at an angle'to the axis of the next adjacent throat in said tube, adjacent tubes being arranged parallel and so that adjacent tube throat axes lying in the same plane are disposed at an angle of about 90 to each other and at an angle of which is disposed at a right angle to the longitudinal axis of the tube, the axis of' one throat being disposed at a right angle to the axis of thenext adjacent throat in said tube, adjacent tubes being arranged parallel and so that adjacent tube throat axes lying in the same plane are disposed at an angle of about 90 to each otherand at an angle of about 45 to the plane of adjacent tubes, and means connecting adjacent tubes approximately 'at points where the ends of adjacent tube throat axes lying inthe same plane most closely approach each other.

4. Heat exchange apparatuscomprising headers and a plurality of tubes between said headers, each tube including a plurality of restricted throats and a plurality of chambers connected' by a restricted elongated throat having an elongated cross-section the longest axis of which is disposed at an angle to the longitudinal axis of the tube, the axis of one throat being disposed at an angle to the axis of the next adjacent throat in the tube, adjacent tubes being arranged Parallel and so that adjacent tube throat axes lying in the same plane are disposed at an angle to each other and at an angle to the plane of adjacent tubes, and means connecting adjacent tubes approximately at points where the ends of adjacent 5. Heat exchange apparatus comprising upper and lower horizontal headers and a plurality of vertical tubes between said headers, each tube including a plurality of restricted throats and a plurality of chambers connected by a restricted elongated throat having anelongated cross-section the longest axis of which is disposed at a right angle to the vertical axis of the tube, the axis of one throat being disposed at a right angle to the'axis of the next adjacent throat in the tube, adjacent tubes being arranged vertically and so that adjacent tube throat axes lying in the same horizontal plane are disposed at an angle of about 90 to each other and at an angle of about 45 to the plane of adjacent tubes, spot welds connecting adjacent tubes approximately at points where the ends of adjacent tube throat axes lying in the same plane most closely approach each other, and means for flowing fluid heat transfer medium in the form of relatively thin films over the surface of said tubes.

I 6.' Heat exchange apparatus comprising a plurality of tubes, each tube including a plurality of chambers connected by a restricted elongated throat having an elongated cross-section the longest axis of which is disposed at an angle to the longitudinal axis of the tube, adjacent tubes being arranged parallel and so that adjacent tube throat axes lying in the same plane are disposed at an angle to each other and at anangle to the plane of adjacent tubes, and means connecting adjacent tubes approximately at points where the ends of adjacent tube throat axes lying in the same plane most closely approach each other.

7. Heat exchange apparatus comprising a plurality of tubes, each tube including a plurality of chambers connected by a restricted elongated throat having an elongated cross-section the longest axis of which is disposed at an angle to the longitudinal axis of the tube, adjacent tubes being arranged parallel and so that adjacent tube throat axes lying in the same plane are disposed at an angle of about to each other and at an angle of about 45 to the plane of adjacent tubes, and means connecting adjacent tubes approximately at points where the ends of adjacent tube throat axes lying in the same plane most closely approach each other.

8. Heat exchange apparatus comprising a plurality of units each including headers and a plurality of tubes between said headers, each tube including a plurality of restricted throats and a plurality of chambers connected by a restricted elongated throat having an elongated cross-section the longest axis of which is disposed at an angle to the longitudinal axis of the tube, the axis of one throat being disposed at an angle to the axis of the next adjacent throat in the tube, ad-

'jacent tubes in a unit being arranged parallel and so that adjacent tube throat axes lying in the same plane are disposed at an angle to each other and at an angle to the-plane of adjacent tubes, means connecting adjacent tubes of a unit approximately at points where the ends of adjacent tube throat axes lying in the same plane most closely approach each other, and means for flowing fluid medium first through the tubes of one unit and then through the tubes of a succeeding unit. 9. Heat exchange apparatus comprising a plurality of vertically disposed units each including horizontally disposed upper headers, a common lower header and a plurality of vertical tubes between said upper and lower headers, each tube including a, plurality of restrictedthroats and a plurality of chambers connected by .a restricted elongated throat having an elongated cross-secition the longest axis of which is disposed at a right angle to the vertical axis of the tube,'the

axis of one throat being disposed at a right angle to the axis of the next adjacent throat in the tube, adjacent tubes in a unit being arranged vertically and so that adjacent tube throat axes lying in the samehorizontal plane are disposed at an angle of about 90 to each other and-at an 'angle of about 457 to the plane of adjacent tubes,

ANDREW M. HARKNESS. 

